About Optics & Photonics TopicsOSA Publishing developed the Optics and Photonics Topics to help organize its diverse content more accurately by topic area. This topic browser contains over 2400 terms and is organized in a three-level hierarchy. Read more.

Topics can be refined further in the search results. The Topic facet will reveal the high-level topics associated with the articles returned in the search results.

Abstract

In this paper, we introduce a novel approach for optical sensing based on the excitation of critically localized modes in two-dimensional deterministic aperiodic structures generated by a Rudin-Shapiro (RS) sequence. Based on a rigorous computational analysis, we demonstrate that RS photonic structures provide a large number of resonant modes better suited for sensing applications compared to traditional band-edge and defect-localized modes in periodic photonic structures. Finally, we show that enhanced sensitivity to refractive index variations as low as Δn=0.002 in RS structures results from the extended nature of critical modes and can enable the fabrication of novel label-free optical biosensors.

Figures (8)

The radiation power spectra of a TM-polarized line source located at the center of (a) periodic square lattice and (b) aperiodic Rudin-Shapiro lattice of dielectric cylinders (ε=10.5, r/a=0.2) in air. Two cluster sizes are considered for each configuration: (a) 5a×5a, Nc=36 (red) and 9a×9a, Nc=100 (blue); (b) 7a×7a, Nc=32 (red) and 15a×15a, N=120 (blue). The green line in Fig. 1(a) shows the radiation spectrum of the 10a×10a (Nc=121) periodic structure with a single defect.

(a). Shifts of resonant wavelengths of TM modes of the Rudin-Shapiro structure (blue) as well as the TM band-edge modes and a point-defect monopole mode of the periodic structure (red) with the change of the analyte refractive index by Δn=0.002; (b) Q-factors of the corresponding modes. The gray area indicates the band-gap of the periodic lattice. The dashed line shows the level of the largest wavelength shift achievable in the periodic structure.

Sensitivities of TM modes of the Rudin-Shapiro structure (blue circles), the TM bandedge modes (red circles), and a point-defect monopole mode (red diamond) of the periodic PhC as a function of (a) the filling fraction of the mode field energy in the host medium and (b) the normalized effective mode volume. Dashed line is obtained by using Eq. 5 for λ=1.55 µm.

The radiation power spectra of a TE-polarized line source located at the center of (a) periodic square lattice and (b) aperiodic Rudin-Shapiro lattice of dielectric cylinders (ε=10.5, r/a=0.2) in air. Two cluster sizes are considered for each configuration: (a) 5a×5a, Nc=36 (red) and 9a×9a, Nc=100 (blue); (b) 7a×7a, Nc=32 (red) and 15a×15a, Nc=120 (blue).

(a). Shifts of resonant wavelengths of TE modes of the Rudin-Shapiro structure (blue) and a TE Bloch mode of the periodic structure (red) with the change of the analyte refractive index by Δn=0.002; (b) Q-factors of the corresponding modes. The dashed line shows the level of the largest wavelength shift achievable in the periodic structure.